Anticorrosive



Patented Nov. 28, 1944 UNITED STATES PA FFIC I 2,363,792 f g ANTICORROSIVE Edward J. Jahn, Edwardsville. Ill., assignor to,

Shell Development Company, San Francisco, Calif., a corporation ofDelaware 18 Claims.

and are relatively inexpensive.

Metallic surfaces, particularly those containing iron, requireprotection against the hazard of corrosion in the presence of water. Toillustrate: Moisture readily attacks finished or semiflnishedmetalobjects unless the metal sm'face is covered during storage. or shipmentby a protective coating such asa slushing oil; water in Diesel enginefuelsoften corrodes closely fitted parts such as are, found in Dieselengine unit type injectors; water in turbines c'orrodes turbinelubricant circulatory systems, particularly the governor mechanisms ofsteam turbines; and water in hydrocarbon oilssuch as gasoline rustssteel storage tanks and drums; water in antifreeze compositions causescorrosion in automobile radiators, etc. Corrosion not only has adeleterious effect upon the metal surfaces, but also frequently loosensfinely dividedmetal oxides which may act as oxidation catalystsincreasing the rate of deterioration of various organic compounds withwhich they come in contact or may enter between moving parts ofmachinery where they act as abrasives, f M

It is a purpose of this invention to produce potent corrosion-protectivecompositions of wide applicability. Another purpose is to produceslushing compositions of improved corrosion-protective properties. Aspecific purpose is to produce rust-protective hydrocarbon compositions,i. e., including variousDiesel oils, steam turbine oils, greases, etc.Still another purpose is to provide anti-freeze compositions free from atendency to cause rusting. Further, it is a purpose to produce anon-oily composition which can be usedfor rust-protection of ferrousmetals and in general for protecting various metals against corrosion. l1

, I. havediscovered that condensation products between maleic acid.androsin acids such as abietic acid in which the"'abietic acid carboxylradical is esterified, are extremely potent corrosion inhibitors ofhighthermalstability, being stable up to about 650 F., particularly whenfinely dispersed in low concentration in a suitable vehicle.

It is known that the relatively high molecular weight condensationproducts between""-maleic acid and olefins are potentcorrosion'inhibitors when dissolved in low concentrations in hydrocarbonoils. However, one of their disadvantages is that they begin todecompose when their solutionis heated to above about 500 F. This hasthe effect that in internal combustion engines, for instance, oilscontaining this anti-corrosive agent will gradually lose theircorrosion-protective properties. Therefore, an anti-corrosive of betterthermal stability would definitely be desirable.

The manufacture of my condensation product is very simple. Aboutequimolal quantities of maleic acid anhydride, unsaturated rosin acidand a suitable alcohol are mixed, and the mixture is first heated undertotal reflux to about 450 F. for an hour orso. Water is removed; Thetemperature is then raised to about 600 F.'for approximately two hours.At the end of this period, the temperature is lowered to about 450 F;and steam or other inert gas is blown throughthe reaction mixturetoremove unreacted ingredients. The steaming should be continued for abouttwo hours at 450. F. and for one hour at 280-300 F; because it alsoserves to convert the anhydride radical of the condensation product'tothe free dicarboxylic acid. When this is accomplished,

tionfrom a lower alcohol having not more than about 6 carbon atoms.

The reaction product is jstableup to about600 F. even though it containsat least 1 andjprobably 2 olefinic double bonds. If desired, thisproduct may be hydrogenated toeliminate these double bonds, therebymaking the compound still more resistant to decomposition and oxidation.Instead of saturating the olefinic double-bonds with hydrogen; theymaybe saturated withsulfur or chlorine or both,thereby imparting to thecompound mild extreme pressure properties."

Rosin acids are unsaturated polyalicyclic hydrocarbon carboxylic acids,abietic acid being a typical rosin acid. They are obtained from talloil, Swedish rosin and other by-products of the pulp paper industry. l rj Alcohols suitable for the esterification should be aliphatic,preferably having 10 or morecarbon atoms, i. e., 12 to 24; carbon atoms.Ifthealcohol is relatively low-boiling, considerable pressure may haveto be applied during thefreactlon,*and

the resulting condensation product is relatively not readily react, andit is dimcult to effect the desired esteriflcation with any alcoholother than aliphatic alcohol.

Insteadof rosin acids, other hydrocarbon carboxylic acids" of or morecarbon atoms having 2 or more oleflnic double bonds, such as olyolefinicunsaturated fatty acids, may be employed. However, it is usuallynecessary to carry out the condensation with a smaller amount of themaleic acid anhydride than would be required to react with all of thedouble bonds of the fatty acid molecules, otherwise a resinous acid ofhigh melting point and high neutralization number will form which is notonly totally insoluble in hydrocarbon oils and most-other solvents, butis also dlfllcult to disperse colloidally. For this reason, it isdesirable, at least when using polyoleflnic' is observed, the reactionproducts are soft, plastic masses of relatively low melting temperatureswhich are considerable soluble in hydrocarbon.

oils.

Suitable polyolefinic fatty acids include geranic acid, linoleic acid,linolenic acid, eleaosteario acid, fish oil fatty acids, seal oil fattyacids, tung oil fatty acids, fatty acids separated as the extract in theselective solvent extraction of mixed fatty acids from various dryingand semi-drying oils, e. g., linseed oil, rapeseed oil, cottonseed oil,soya bean oil, corn oil, rice oil, sesame oil, mustardseed oil, etc.

To produce, the anti-corrosive composition, a small amount of theesterified condensation product is finely dispersed in a suitablevehicle. The dispersion may be a true or colloidal solution.

or naphthenic acids, may be present, and in many instances thismay evenbe beneficial.

Both polar and non-polar vehicles may be employed. Among the former arewater, alcohols, such as methyl, ethyl, propyl, isopropyl,,butyl, amyl,hexyl, cyclohexyl, heptyl, methyl cyclohexyl, octyl, decyl, lauryl,myrlstyl, cetyl, stearyl,

, benzyl, eto., alcohols; polyhydric alcohols as eth- True solutions arein general preferred whenever a they can possibly be obtained, firstbecause colloidal solution may cause emulsification between anoleaginous vehicle and water which may be very undesirable, and second,because colloids may precipitate, in which case at least a portion ofthe active ingredient is removed.

The vehicles to which the dicarboxylic acids of this invention maybeadded for the purpose of producing corrosion-protective compositions maybe divided intoseveral groups. In the first place, they may be liquidsor plastics, the only requirements as to their physical state being (inaddition to their being abl to act as carrier for the acids under normalatmospheric conditions) that they be spreadable over metal surfaces.Spreading may be accomplished by immersing, flooding,

spraying, brushing, trowelling, etc.

After being applied, all or part of the vehicle may evaporate, or it maybe more or less permanent. In other words, both volatile carriers may beused, or substances which do not materially volatilize, under normalatmospheric conditions. As to chemical requirements, the vehicle must bestable under ordinary conditions of storage and use and be inert to theactive inhibitors.

Thus the vehicle should preferably be substantially neutral, although itmay be weakly acidic or basic, preferably having dissociation constantsnot above about 10-". In vehicles of low dielectric constant, ashydrocarbon oils, which are not conducive to ionization of dissolvedelectrolytes, relatively small amounts, i. e., about .l%-5% of variouscarboxylic acids, such as fatty ylene glycol, propylene glycol, butyleneglycol, glycerol, methyl glycerol, etc.;' phenol and various alkylphenols; ketones as acetone, methyl ethyl ketone, diethyl ketone, methylpropyl, methyl butyl, dipropyl ketones, cyclohexanone and higherketones; keto alcohols as benzoin, ethers as diethyl ether, diisopropylether, diethylene dioxide,

beta-beta dichlor diethyl ether, diphenyl oxide, chlorinated diphenyloxide, diethylene glycol, triethylene glycol, ,ethylene .glycol monomethyl ether, corresponding ethyl, propyl, butyIQethers; neutral estersof carboxylic and other "acids as ethyl, propyl, butyl, amyl, phenyl,cresyl and higher acetates,.propionates, butyrates, lactates, laurates,myristates, palmitates, stearates, oleates, ricinoleates, rphthalates,phosphates, phosphites, thiophosphates, carbonates; natural waxes asCarnauba wax, candellila wax, Japan wax, jojoba oil, sperm oil; fats astallow, lard oil. olive oil, cottonseed -oil, perilla oil, linseed oil,

tung oil, soya bean oil, flaxseed oil, etc.;- weak bases as pyridine,alkyl Dyridines, quinolines, petroleum bases, etc.

Vehicles of little or no polarity comprise hydrocarbons or halogenatedhydrocarbons as liquid butanes, pentanes, hexanes, heptanes,'octanes,benzene, toluene, xylenes, cumene, indene, hydrindene, alkylnaphthalenes; gasoline distillates, kerosene, gas oil, lubricating oils(which may be soap-thickened to form greases), petrolatum, paraflln wax,albino asphalt; carbon tetrachloride, ethylene dichloride, propylchloride, butyl chloride, chlor benzol, chlorinated kerosene,chlorinated paraflin wax, etc.

The amounts of the dicarboxylic acids which must be incorporated in theabove vehicles to produce corrosion-protective compositions varyconsiderably with the type of vehicle used. As a general rule, thepresence of resinous materials, particularlyv those of a colloidalnature, calls for relatively larger amounts of inhibitors. Resinousmaterials which interfere with the activity of the inhibitors compriseasphaltenes, petroleum resins, various other natural resins, as rosin,resins formed by polymerization of drying fatty oils,phenol-formaldehyde resins; glyptal type resins formed by esteriflcationof polyhydric alcohols with polycarboxylic acids, etc.

In the absence of such resinous materials,

amounts required of the dicarboxylic acids vary from about .001% up toabout .1%, although larger amounts may be used. However, where the acidsare in colloidal dispersion, rather than in true solution, aconcentration in excess of about .1% may result in relatively quick lossof Since resinous and gummy substances in the vehicles do call forgreater amounts of inhibitors, it isusually desirable to refine normallyliquid vehicles thoroughly and free them from gummy asesnaa substances,thereby imparting to them maximum inhibitor susceptibility. This is ofparticular importance, for example, in lubricating oils, specificallysteam turbine oils, which are advantageously highly refined before theinhibitor is introduced. Suitable refining treatments include, forexample. extraction with selective solvent for aromatic hydrocarbons asliquid S02, phenol, furfural, nitrobenzene, aniline,beta-beta-dichlorine diethyl ether, antimony trichloride, etc; treatmentwith Alcla,sulfuric acid, clay, etc. If the treatment produces a sludge,special care must be taken to remove it very thoroughly and completely.

pplications of the various corrosion-protective, I

compositions vary over a wide range. Hydrocarbon compositions are ofspecial importance. For example, gasolines stored in drums may, causerusting of the drums because of the accumulation of water. This isparticularly bad in tropicalwith which they came in contact, such asbearings, crank-eases, shafts, etc. This problem arises in many types ofengines and is often particularly serious in steam turbines. Thepresence of the inhibitors of this invention will afford excellentprotection in all of the above instances.

Busting of ferrous metals exposed to the atmosphere during usage orstorage is a serious problem. This is of particular importance whereaccurately machined parts must be preserved. Slushing oils comprisingvarious types of liquid or plastic hydrocarbons, fats, waxes, lanolin,are employed to protect the metals against this attack, and theinhibitors of this invention have great value as an active component insuch slushing oils.

Cutting oils, EP lubricants, due to their content, of sulfur and/orchlorine in variou active'forms, frequently are quite corrosive. Thedicarboxylic di-fatty acids efiectively inhibit this corrosion.

Among the non-hydrocarbon compositions which frequently cause corrosiondifficulties, anti? freezes used in automobile radiators and the likemay be mentioned. The dicarboxylic acids effectively eliminate theircorrosiveness. Antifreezes usually comprise or consist of water-misciblealcohols, such as methanol, ethanol, isopropanol, glycol, glycerol, etc.

So-called hydraulic oils, damping oils, etc., which frequently are basedon non-hydrocarbon liquids, such as various alcohols, esters, etc., havein the past introduced some corrosion dificulties which can eiiectivelybe prevented by the acids of this invention. I

Dispersions of the dicarboxylic di-fatty acids in water may be useful inthe rust-proofing of metals which after treatment must not be greasy as,for example, various machine parts in the textile industries,particularly in the knitting of fine dry goods. If desired, solutions ordispersions in low-boiling alcohols, etc., may be used for b the samepurpose.

gredients must be chemically inert to theaeid and the vehicle employed.Thus strong oxidizing agents as chlorine, peroxides, etc., must beavoided as they tend to destroy the inhibitors. Strong bases,particularly in ionizing vehicles, as in water, alcohols, etc., willneutralize the diacids and thereby render them relatively ineffective.Likewise, strong acids may reduce their eflectiveness. However, innon-ionizing solvents.

i. e., in hydrocarbon compositions, chlorinated hydrocarbons, etc., thepresence. of relatively small quantities of primary, secondary andtertiary nitrogen bases and/or carboxylic acids will not normallyinterfere with the activity of the inhibitor. On the other hand, even inthese vehicles very strong bases as various onium bases, or very strongacids as sulfonic acids, should not be present.

Accordingly, hydrocarbon compositions and the like may contain varioustypes of oxidation inhibitors as alkylated phenols, aromatic amines,preferably secondary amines-amino phenols; as well as various EPcompounds containing halogen, S, P, As, etc., anti-wear compounds,detergents, sludge-preventing compounds, pour point reducers,thickeners, such assoaps, etc. Likewise, fats, anti-freezes, etc., maycontain anti-oxidants.

Example T Equimolal quantities of maleic acid anhydride,

' abietic acid and stearyl alcohol were reacted in the manner'describedbefore. .01% of the reaction product was dissolvedin. a highly refined100 F. of'150 seconds.

steam turbine oil having a Say. Univ. viscosity of Two polished steelstrips were immersed invigorously stirred emulsions of said oil with 10%distilled water and seawater,

' respectively, for 48 hours at 167 F. Both strips remained blank,showing no signs of corrosion.

I claimas my invention: b

1. A corrosion-preventive. composition comprising predominantly astable, substantially neutral vehicle containing finely dispersed acorrosion inhibiting amount, less than 5% of a free dicarboxylic acidbeing the hydrolyzed condensation product between maleic acid anhydrideand a polyoleflnic hydrocarbon carboxylic acid! having at least 10carbon atoms, the ca'rboxyl radical of said hydrocarbon carboxylic acidbeing esterified with an aliphatic alcohol.

2. The composition of claim 1 wherein the alcohol has at least 10 carbonatoms.

3. The composition of claim 1 wherein the alcohol has from 12-24 carbonatoms.

4. The composition of claim 1 wherein the carboxylic acid is abieticacid.

5. The composition of claim l-wherein said vehicle has a dissociationconstant below 10'.

6. The composition of claim 1 wherein said acid is in true solution. a

'7. The composition of claim 1 wherein said acid is in colloidalsolution.

8. A corrosion-preventive composition comprisvehicle containing finelydispersed a corrosion inhibiting amount, less than 5% of a free di-' 1carboxylic acid being the hydrolyzed condensation product between maleicacid anhydride and an unsaturated rosin acid, the carboxyl radical ofthe rosin acid being esterifled with an alcohol.

9. A corrosion-preventive composition comprising predominantly a stable,substantially neutral vehicle containing finely dispersed a corrosioninhibiting amount, less than 5% of a free dicaraliphatic Q boxylic acidbeing the hydrolyzed condensation product between maleic acid anhydrideand a polyoleflnic fatty acid having at least 10 carbon atoms, thecarboxyl radical of the fatty acid being esterifled with analiphaticalcohol.

10. A corrosion-preventive composition comprising predominantly asubstantially neutral oleaginous substance containing a corrosioninhibiting amount, less than of a free dicarboxylic acid being thehydrolyzed condensation product between maleic acid anhydride and apolyolefinic hydrocarbon carboxylic acid having at least carbon atoms,the carboxyl radical or the hydrocarbon carboxylic acid being esterifledwith an aliphatic alcohol.

' 11. The composition of claim 10 in which said substance is normallyliquid.

12. The composition of claim 10 in which said substance is normallyplastic. I

13. A corrosion-preventive composition comprising predominantly asubstantially neutral oleaginous substance free from resins containingfinely dispersed..001%.l% of a free dicarboxylic acid being thehydrolyzed product of condensation between maleic acid anhydride and apolyoleflnic hydrocarbon carboxylic acid having at least 10 carbonatoms, the carboxyl radical of the hydrocarbon carboxylic acid beingesterified with aliphatic alcohol. v

14. A corrosion-preventive composition comprising predominantly asubstantially neutral oleaginous substance containing resins and finelydispersed .1%-5% of a free dicarboxylic acid being the hydrolyzedproduct of condensation between maleic acid anhydride and a polyolefinichydrocarbon carboxylic acid having at least 10 carbon atoms, thecarboxyl radical of the hydrocarbon carboxylic acid being esterifiedwith aliphatic alcohol.

15. A corrosion-preventive lubricatingoil 0011- taming finely dispersed.001%-1% of a i'ree dicarboxylic acid being the hydrolyzed product 01'condensation between maleic acid anhydride and a polyoleflnichydrocarbon carboxylic acid having at least 10 carbon atoms, thecarboxyl radical of the hydrocarbon carboxylic .acid being esterihadwith aliphatic alcohol.

16. A corrosion-preventive composition comprising a carboxylic acidester containing finely dispersed a corrosion inhibiting amount, lessthan 5% of a free dicarboxylic acid beingthe hydrolyzedproduct ofcondensation between maleic acid anhydride and a polyolefinichydrocarbon carboxylic acid having at least 10 carbon atoms, thecarboxyl radical of the hydrocarbon carboxylic acid being-esterifiedwith aliphatic alcohol.

1'7. A corrosion-preventive. composition comprising a fat and finelydispersed therein a cor-' rosion inhibiting amount, less than 5% of afree dicarboxylic acid being the hydrolyzed product of condensationbetween maleic acid anhydride and a polyolefinic hydrocarbon carboxylicacid.

having at least 10 carbon atoms, the carboxyl radical of the hydrocarboncarboxylic acid being esterified with aliphatic alcohol.

18. A non-corrosive anti-freeze composition comprising a water-solublealcohol and finely dispersed therein a corrosion inhibiting amount, lessthan 5% of a free dicarboxylic acid being the hydrolyzed product ofcondensation between maleic acid anhydride and a polyolefinichydrocarbon carboxylic acid having atleast 10 carbon atoms, the carboxylradical of the hydrocarbon carboxylic acid being esterifled withaliphatic alcohol.

EDWARD J. J AHN.

